Rivermill Hydro Dam dam
Rivermill Hydro Dam
Rivermill Hydro Dam, also known as Hdi Mascoma, is a private hydroelectric structure located in Lebanon, New Hampshire along the Mascoma River. Completed in 1925, this concrete dam stands at a height of 22.4 feet and has a length of 300 feet. With a normal storage capacity of 170 acre-feet and a maximum storage of 210 acre-feet, the dam serves as a crucial source of renewable energy for the region.
Despite its age, Rivermill Hydro Dam has faced challenges in terms of its condition assessment, which was rated as poor during the last inspection in August 2018. The dam has been designated with a high hazard potential, emphasizing the need for regular monitoring and maintenance to ensure its safety and functionality. While the hazard potential is high, the overall risk assessment for the dam is categorized as moderate (3), indicating a manageable level of risk with appropriate risk management measures in place.
As a significant contributor to the local hydroelectric power generation and water resource management, Rivermill Hydro Dam plays a vital role in supporting the sustainable development and resilience of the surrounding communities. Its historical significance and continued operation highlight the importance of balancing energy production with environmental conservation and safety considerations in the face of changing climate patterns and water resource management challenges.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Rivermill Hydro Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Connecticut River At West Lebanon | 24,000 cfs | → |
| Ottauquechee River At North Hartland | 658 cfs | → |
| White River At West Hartford | 2,330 cfs | → |
| Ompompanoosuc River At Union Village | 16 cfs | → |
| Sugar River At West Claremont | 1,190 cfs | → |
| Baker River Near Rumney | 1,050 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Rivermill Hydro Dam.
Boat launches
- Connecticut River Boat Launch
- Mascoma Lake Boat Launch
- Crystal Lake Boat Launch
- George Pond Boat Launch
- Grafton Pond Boat Launch
- Mcdaniels Marsh Boat Launch
Campgrounds
Fishing spots
Paddle runs
- Source Above Fr 55 To Proclamation Boundary (Stony Brook)
- Headwaters To Woodstock, Vt
- Begins In Franklin To Sewall's Island
- Thornton Railroad Bridge To Bridgewater/Bristol Town Line
- Headwaters To Crossing Of Route 100 Near Route 155
- Woodstock/Thornton Town Line To Thornton Railroad Bridge
Track Rivermill Hydro Dam in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Rivermill Hydro Dam
Where does the data for Rivermill Hydro Dam come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the High hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Rivermill Hydro Dam.